The LI190SB-L measures photosynthetically active radiation (PAR), a spectral range of solar radiation from 400 to 700 nm. This is the energy that plants use during photosynthesis. Measurements with the LI190SB-L are reported as photosynthetic photon flux density (PPFD).
The LI200X-L measures total solar radiation from 400 to 1100 nm. Measurements are usually reported in units of W/m2.